What is the equivalent resistance between points A and B of the networks of resistors.

Explanation

In this network of resistors, one end of each of `R_(1),R_(2)and R_(3)` is connected to point B and their other end to point O. One end of `R_(4)` is connected to point O and the other end to point A. Thus the equivalent circuit will be as shown in figure.

Here, `R_(1), R_(2) and R_(3)` are in parallel and `R_(4)` in series. The effective resistance of `R_(1),R_(2) and R_(3)` in parallel will be
`1/R' = 1/R_(1) + 1/R_(2) + 1/R_(3) = 1/3 + 1/4 + 1/5 = 47/60`
or `R' = 60/47 Omega`
`:.` Equivalent resistance between A and B
`= R' + R_(4) = 60/47 + 6 = 342/47 = 7.28 Omega`